Direction-indicator for air and marine craft



F. L. AND J. B. PENTZ.

OIREOTION INDICATOR FOR AIR AND MARINE CRAFT.

APPLICATION FILED FEB- 23; 1918.

1,375,727.. Patented May 3, 1921.,

VINVENTORS Flore/Zea L. a d

James B Pang], BY

ATTORNEYS UNITED STATES PATENT OFFICE.

FLORENCE LYOIT PENTZ AND JAMES BOLTON PENTZ, OF NEW YORK, N. Y.

DIRECTION-INDICATOR FOB, AIR AND EARINEURAIT.

Specification of Letters latent.

Application flied February 28, 1918. Serial No. 218,646.

To all whom it may concern:

Be it, known that we, FLORENCE LYON PnN'rU and J AMES BOLTON PnN'rz, both citizens of the United States, residing at New York, count New York, ave invented certain new and useful Improvements in Direction-Indicators for Air and MarineCraft, of which the following is a full, clear, and exact description.

This invention relates to combined compasses and levels for aircraft, particularly airplanes, and its chief object is to provide a simple and reliable device which will indicate to the aviator the direction of flight both in the horizontal and the vertical plane.

Another object is to provide for the purpose which may be conveniently realized in prac' tice by a magnetic compass needle and a Supportfonthe same which will act in the mannor of aplumblin e, so to speak, are immersed in a body of liquid contained in a suitable transparent receptacle, preferably a sphericalrglobe. The receptacle is movable freely about the body of liquid, practically the only opposition to such movement being the slight friction or drag between the, two; and by preference the aforesaid devlces are so shaped as to impede their movement in or relatively to the liquid, thereby locking the said devices and the liquid together, as it were. The result is that the movements of the receptacle about the liquid have substantially no effect upon the aforesaid devices, which thereforecontinue to point in their normal directions.

Referring to the accompanying drawing,

Figure 1 is a side view of one form of our improved compass.

Fig. 2 is a side view of the same, but with part of the globe broken away, and showing of Richmond, and Stateofspherical as possible.

the position of the device when the airplane or other aircraft is tipped or tilted at a stegp angle to the horizontal.

1g. 3 is a crosssection of the preferred form of the invention.

Fig. 4 is a sectional plan view on line 4-4 I of Fig. 3.

Our improved compass as illustrated comprises a hollow transparent globe 10, made of glass orother suitable material, and preferably having at least its inner surface asnearly In the embodiments shown in Figs. 1. to et inclusive the globe is filled or nearly filled with a suitable liquid, preferably of low freezing point so as not to solidify when subjected to the intense cold often encountered in flight, especially at high altitudes. Among the liquids suitable for the purpose, alcohol and gasolene may be mentioned. To permit expansion and contraction of the liquid due to the extremes of temperature to which it is subjected a chamber 11 may be provided in the stem or neck 10 of the globe,communicating with the interior by a narrow'passage and closed on the outside by means of a yielding or elastic diaphragm, as 12, secured in osition in-any convenient manner. Or, b lling the globe not quite full, a bubble 0 or vapor, inside. resorted to. Theportion containing the expansion chamber, and, if desired, the adja- Patented May 3, 1921.

cent portion of the globe itself, may be made of metal, as in such parts transparency 1S not,'in general, essential.

Immersed in the liquid in the globe is a magnetic needle 14, suspended by a rod 15 from a suitable float 16. The buoyancy of the latter or the weight of the parts supported by it is preferably such that the point or finger 17 at the top will at most barely graze the inner surface of the globe when the liquid is at aboutits maximum density. In the embodiment shown, the needle 14 is ri idly attached to the bar or rod 15.

n order toput the center of gravity well below the float 16 a weight 18 is provided, preferably of non-magnetic material. In the present instance the weight is mounted on the stem near the lower end thereof. To damp the needle and thereby diminish its movements relative to the liquid in which the parts are immersed, the stem is made of a flat bar, or the needle, also made of similar shape, is set on edge. Or both these expedients may be resorted to, the lane of the stem being at right angles to t e plane of the needle so as to diminish the tendency to swing as a pendulum relatively. to the liquid, while the needle itself op oses rotary vibration within the liquid. 11 the other hand, vibration, asfrom a racin engine of motor tends to keep the float rom lagging and hence aids it in keeping its position at the extreme top of the globe as the latter is tilted.

The lobe is preferably made in two parts, divider? at the horizontal diameter. After the floating parts are inserted the globeparts are secured together in any convenment and suitable manner, as by means of insoluble cement, so as to make a liquid-tight joint. If necessary or desirable the 'oint so made may be reinforced with ban 19, preferably of spring brass, which has a spherical inner surface so as to fit the globe snugly. The band may be a simple ring of slightly smaller diameter than the globe, so that it can besprun into place.

In the preferred em odiment, Figs. 3 and 4, the stem 15 carries a compass card 20,

reaching nearly to the wall of the globe, and the stem is of such length as to position the card. at the central horizontal plane of the globe, as shown. The card, which is preferabl made of non-magnetic metal, as brass or a uminum, may be marked with the points of the compass like the mariners compass or in any other convenmm and suitable manner. For indicating azimuth, or horizontal direction, marking of some sort on the card is of practical importance if the needle is below the card, as in Figs. 3 and 4. Both sides of the card may be marked, so"that when flyin upside down the points of the com ass can e read; and the two sides may be 0 different colors, for example, white and red, so that they can be distinguished at a glance.

' The only impediment to the rotary moveinent of the globe (in any plane), relatively to the body of liquid inside is the skin-friction between the two. his being very slight considering the total mass and therefore the considerable inertia of the liquid, the lobe exerts but little drag on the liquid. Hence when the globe is fixed to the airplane (and is therefore stationary relativel thereto) the rotary movement of the glo e in any plane as the airplane changes the direction of its flight is communicated to the liquid only to a slight extent, if at all. In short, the globe rotates around the liquid. The normally slight tendency of the liquid to turn with the globe is further reduced by the reluctance of the needle (and hence of the parts connectedwith it) to depart from the north and zontal stationar south direction, which reluctance is commun'icated to the liquid by the resistance to movement of the arts relatively to the liquid by reason of the skin-friction of the liquid and such parts and by the flat shape of the card, needle and stein. In other words, the needle and connected parts tend to remain always invthe position established by the needle under the influence of the earths magnetism, and the li uid clin to the needle and other parts so t at the hquid itself tends to remain in the position established by the needle. Hence the liquid and the parts immersed therein act more or less as a solid body about which the globe is freely movable. Theresult is that as the airplane tilts and turns, the needle continues to point to the north, the stem maintains its vertical or plumb-line position, and the card and needle maintain-the horiposition. The globe is preferabl marked or graduated,'as for exam 1e wit horizontal and vertical circles, l' e parallels of latitude and meridians of Ion tude on a terrestial globe. Then as t e globe turns about the liquid and the compass-parts therein, fore and aft, side-wise, or in any other direction, the circles or other graduations are carried past the relatively parts immersed in theliquid. Thus if t e air-plane changes. the directions of its flight in the horizontal plane the meridians turn clockwise or counterclock wise, as the case may be. The vertical circle or meridian which is parallel to or in the central vertical plane extending lengthwise of the airplane can be distinctively marked, so that the angle between such meridian or zero-circle and the point of the needle can be easily noted. If the airplane tips or tilts in any direction the parallels move past the index 17 the bubble 13, and the edge of the card 20, thus indicating the position or direction of the airplane with respect to the horizontal. One of the parallels around each pole can be marked in a distinctive manner to indicate a degree of inclination beyond which it is particularly dangerous to go.

The method of supporting the globe 10 is immaterial, and accordingly wehave shown merely a simple .base 25 in which the neck or stem may be fixed by means of cement or otherwise.

It is to be understood that the invention is not limited to the specific devices herein illustrated and described but can be embodied in other forms without departure from its spirit. Nor is the invention limited to use on aircraft, since it may be employed to advantage on other vessels, particularly submarines.

We claim 1. In a direction-indicator or compass for air-craft, a hollow globe filled with a suitable liquid, a floating carrier therein, and a magnetic needle supported solely by the floating carrier and entirely unconnected with the globe, whereby the globe has unlimited freedom of rotation in every direction relative to the needle and at all times leaves the needle entirely free to maintain its normal position.

. 2. In a direction-indicator or compass for air-craft a hollow globe. filled with a suitable liquld, a floating carrier therein, a compass-card and a magnetic needle rigidly attached to the card, supported solely by the floatin carrier and entirely unconnected with t e globe, whereby the globe has unlimited freedom of rotation in every direction relatively to the needle and card and to maintain their normal position.

3. In a direction-indicator or compass for aircraft, a hollow globe filled with'a suitable liquid, a float therein, a vertical stem carried by the float, and a magnetic needle carried by the stem,,the needle being supported solely by the stem andfloat and being entirely unconnected with the globe, whereby the globe has unlimited freedom of rotation in eve direction relative to the needle and at all times leaves the latter free to maintain its normal position. I

In testimony whereof we hereunto aflix our signatures.

FLORENCE LYON PENTZ. JAMES BOLTON PENTZ.

at all times leaves the needle and card free 

